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TOMOYO Linux Cross Reference
Linux/fs/proc/namespaces.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 #include <linux/proc_fs.h>
  3 #include <linux/nsproxy.h>
  4 #include <linux/ptrace.h>
  5 #include <linux/namei.h>
  6 #include <linux/file.h>
  7 #include <linux/utsname.h>
  8 #include <net/net_namespace.h>
  9 #include <linux/ipc_namespace.h>
 10 #include <linux/pid_namespace.h>
 11 #include <linux/user_namespace.h>
 12 #include "internal.h"
 13 
 14 
 15 static const struct proc_ns_operations *ns_entries[] = {
 16 #ifdef CONFIG_NET_NS
 17         &netns_operations,
 18 #endif
 19 #ifdef CONFIG_UTS_NS
 20         &utsns_operations,
 21 #endif
 22 #ifdef CONFIG_IPC_NS
 23         &ipcns_operations,
 24 #endif
 25 #ifdef CONFIG_PID_NS
 26         &pidns_operations,
 27         &pidns_for_children_operations,
 28 #endif
 29 #ifdef CONFIG_USER_NS
 30         &userns_operations,
 31 #endif
 32         &mntns_operations,
 33 #ifdef CONFIG_CGROUPS
 34         &cgroupns_operations,
 35 #endif
 36 };
 37 
 38 static const char *proc_ns_get_link(struct dentry *dentry,
 39                                     struct inode *inode,
 40                                     struct delayed_call *done)
 41 {
 42         const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
 43         struct task_struct *task;
 44         struct path ns_path;
 45         void *error = ERR_PTR(-EACCES);
 46 
 47         if (!dentry)
 48                 return ERR_PTR(-ECHILD);
 49 
 50         task = get_proc_task(inode);
 51         if (!task)
 52                 return error;
 53 
 54         if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
 55                 error = ns_get_path(&ns_path, task, ns_ops);
 56                 if (!error)
 57                         nd_jump_link(&ns_path);
 58         }
 59         put_task_struct(task);
 60         return error;
 61 }
 62 
 63 static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen)
 64 {
 65         struct inode *inode = d_inode(dentry);
 66         const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
 67         struct task_struct *task;
 68         char name[50];
 69         int res = -EACCES;
 70 
 71         task = get_proc_task(inode);
 72         if (!task)
 73                 return res;
 74 
 75         if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
 76                 res = ns_get_name(name, sizeof(name), task, ns_ops);
 77                 if (res >= 0)
 78                         res = readlink_copy(buffer, buflen, name);
 79         }
 80         put_task_struct(task);
 81         return res;
 82 }
 83 
 84 static const struct inode_operations proc_ns_link_inode_operations = {
 85         .readlink       = proc_ns_readlink,
 86         .get_link       = proc_ns_get_link,
 87         .setattr        = proc_setattr,
 88 };
 89 
 90 static int proc_ns_instantiate(struct inode *dir,
 91         struct dentry *dentry, struct task_struct *task, const void *ptr)
 92 {
 93         const struct proc_ns_operations *ns_ops = ptr;
 94         struct inode *inode;
 95         struct proc_inode *ei;
 96 
 97         inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK | S_IRWXUGO);
 98         if (!inode)
 99                 goto out;
100 
101         ei = PROC_I(inode);
102         inode->i_op = &proc_ns_link_inode_operations;
103         ei->ns_ops = ns_ops;
104 
105         d_set_d_op(dentry, &pid_dentry_operations);
106         d_add(dentry, inode);
107         /* Close the race of the process dying before we return the dentry */
108         if (pid_revalidate(dentry, 0))
109                 return 0;
110 out:
111         return -ENOENT;
112 }
113 
114 static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
115 {
116         struct task_struct *task = get_proc_task(file_inode(file));
117         const struct proc_ns_operations **entry, **last;
118 
119         if (!task)
120                 return -ENOENT;
121 
122         if (!dir_emit_dots(file, ctx))
123                 goto out;
124         if (ctx->pos >= 2 + ARRAY_SIZE(ns_entries))
125                 goto out;
126         entry = ns_entries + (ctx->pos - 2);
127         last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
128         while (entry <= last) {
129                 const struct proc_ns_operations *ops = *entry;
130                 if (!proc_fill_cache(file, ctx, ops->name, strlen(ops->name),
131                                      proc_ns_instantiate, task, ops))
132                         break;
133                 ctx->pos++;
134                 entry++;
135         }
136 out:
137         put_task_struct(task);
138         return 0;
139 }
140 
141 const struct file_operations proc_ns_dir_operations = {
142         .read           = generic_read_dir,
143         .iterate_shared = proc_ns_dir_readdir,
144         .llseek         = generic_file_llseek,
145 };
146 
147 static struct dentry *proc_ns_dir_lookup(struct inode *dir,
148                                 struct dentry *dentry, unsigned int flags)
149 {
150         int error;
151         struct task_struct *task = get_proc_task(dir);
152         const struct proc_ns_operations **entry, **last;
153         unsigned int len = dentry->d_name.len;
154 
155         error = -ENOENT;
156 
157         if (!task)
158                 goto out_no_task;
159 
160         last = &ns_entries[ARRAY_SIZE(ns_entries)];
161         for (entry = ns_entries; entry < last; entry++) {
162                 if (strlen((*entry)->name) != len)
163                         continue;
164                 if (!memcmp(dentry->d_name.name, (*entry)->name, len))
165                         break;
166         }
167         if (entry == last)
168                 goto out;
169 
170         error = proc_ns_instantiate(dir, dentry, task, *entry);
171 out:
172         put_task_struct(task);
173 out_no_task:
174         return ERR_PTR(error);
175 }
176 
177 const struct inode_operations proc_ns_dir_inode_operations = {
178         .lookup         = proc_ns_dir_lookup,
179         .getattr        = pid_getattr,
180         .setattr        = proc_setattr,
181 };
182 

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